The Oxford English Dictionary notes: "The vowel of the modern gloaming is anomalous, as Old English glōmung should normally become glooming. The explanation is probably that the ō was shortened in the compound ǣfen-glommung (as the spelling seems to show was actually the case), and that from this compound there was evolved a new subject glōmung, which by normal phonetic development became Middle English glǭming, modern English gloaming."[1]

You may imagine the young people brushed up after the labours of the day, and making this novelty, as they would make any novelty, the excuse for walking together and enjoying a trivial flirtation. You may figure to yourself the hum of voices along the road in the gloaming...

2001 — David Lodge, Thinks...

I clung to her nipples as she soared and swooped through the gloaming, scooping up insects, and I remember the shapes of things that she flew between, above, beneath.